In a paper ejection tray assembly which is attached to an image reading apparatus or image copying apparatus etc., the phenomenon of paper being ejected from the ejection slot, then the front end part of the paper not being able to advance over a stacking surface of the paper ejection tray assembly or the stacked paper and therefore being bent, i.e., so-called buckling, occurred, and a paper eject jam (paper jam) sometimes occurred. Further, at the time of paper ejection, sometimes not only did the ejected paper buckle, but also the force by which the ejected paper was ejected and the friction between sheets of paper caused stacked paper to be pushed and the paper to fall to the floor.
To prevent buckling of paper at the time of ejection, in the past (1) the landing angle when the paper landed on the paper ejection tray assembly was made smaller, (2) the height from the ejection slot to the paper ejection tray assembly was made smaller, (3) in the ejection slot, paper eject rollers etc. were used to stiffen the paper in the longitudinal direction (paper ejection direction), and other attempts have been made. However, if, like in (1), making the landing angle smaller to an extent where buckling does not occur, the inclination angle of the paper ejection tray assembly also became smaller, so the stacked paper was not aligned at the rear ends and a stopper became necessary at the back end of the paper ejection tray assembly. For this reason, the length of the paper ejection tray assembly became greater than the length of the paper, the paper ejection tray assembly became larger, and the user was consequently inconvenienced. Further, if, like in (2), lowering the height from the ejection slot to the paper ejection tray assembly, the load when the paper landed on the paper ejection tray assembly became smaller, but there was the problem that the maximum stacked capacity of the paper was reduced compared with the past. Further, if, like in (3), using paper eject rollers for stiffening, if the ejection slot and the image reading position were close, the stiffening given at the ejection slot also had an effect on the reading of the image, so a large stiffness could not be given. Further, due to stiffening, the push-off force at the time of ejection increased, so there was the problem that the factors pushing off paper stacked on the paper ejection tray assembly increased.
As the method for prevent push-off and fall-off of the stacked paper, attempts have been made such as providing a stopper at the end of the paper ejection tray assembly and physically stopping the paper which is pushed off or increasing the angle at which the paper ejection tray assembly is set (increasing the inclination angle). However, with each method, push-off and consequent fall-off are prevented, but providing a stopper increases the size of the paper ejection tray assembly and inconveniences the user. Further, when increasing the setting angle, the friction when the ejected paper passes over the stacked paper also increases, so there was the possibility of the paper buckling.
Further, as art for stacking the ejected paper, Japanese Patent Publication No. 2000-327204A discloses forming a cutaway part in a sheet stacking surface which stacks the sheets, providing a movable sheet receiver which can move up and down in this cutaway part, and allowing the movable sheet receiver to descend due to its own weight in accordance with the increase of the number of sheets which are ejected to the sheet stack table so that even curled sheets can be smoothly stacked without reducing the maximum sheet stacking capacity. However, in the art which is described in Japanese Patent Publication No. 2000-327204A, the paper could not be given sufficient stiffness and paper eject jams could occur.
Japanese Patent Publication No. 7-179259A discloses an image forming apparatus in which, when pulling out a slide tray part, a rib-shaped projection is pushed upward for the purpose of preventing an ejected sheet from falling off from a paper ejection tray and enabling stacking to a suitable position at all times. The stacked paper is pushed upward by the rib-shaped projection, but the stacked paper could be pushed off due to friction with the ejected paper.